By simply growing Bacillus anthracis in the presence of sub-inhibitory concentrations of antibiotics it has been made resistant to all commonly used drugs such as penicillin, doxycycline and Ciprofloxacin. If one of these antibiotic resistant strains were used in a future terrorist attack there will be limited or no therapeutic treatments available. Thus there is an urgent need to develop new classes of antibiotics to treat resistant B. anthracis. A shotgun antisense technology is proposed for the rapid identification of B. anthracis essential genes, whose protein products can serve as targets for new classes of antibiotics. This technology conditionally and incrementally reduces the level of an essential gene product, which provides a means to hypersensitize cells to compounds that inhibit that target and thus provides a cell-based assay for drug discovery. Phase I of this proposal will be to develop the molecular biology tools for conditionally delivering random genomic antisense RNA fragments to B. anthracis cells. In Phase II a genome-wide screen in B. anthracis will identify a comprehensive list of essential genes. We have developed a unique microbial relational database, which allows the prioritization of targets based on conservation among bacterial pathogens having no or limited homology to human proteins. Bioinformatics analyses undertaken prior to drug screening should help ensure that new antimicrobial drugs have maximal impact upon the disease and minimal impact on the patient. Cell-based assays will be optimized for these prioritized targets and entered into an established high throughput chemical screening program against the company's chemical library of over 250,000 compounds. This Gene-to-Screen technology platform has been developed to allow miniaturized drug screens to be developed for any validated target within 2-3 weeks. Promising hit compounds would then be rapidly developed and advanced into lead-optimization chemistry. New classes of antibiotics would help deter and treat against future bioterrorist attacks and could also be used to treat common drug resistant pathogens.